The present invention relates to improvements in paper making machines, and more particularly to an improved structure for an extended press nip which permits alignment of the roll and insures continuous self-alignment of the bearings for the main roll.
In a commercial high speed paper making machine for making various types of paper, the paper web is formed and passes through a press section for mechanical extraction of the water and thereafter passes through a dryer section for thermal extraction of the water. A substantial improvement in the press section has been obtained by the provision of extended nip presses which, instead of simply employing two opposed rolls, employ a structure where the web is subjected to a continual pressure for a period of time. One commercially satisfactory arrangement of this type of structure employs a large press roll with an opposed facing concave shoe. A tough belt passes through the nip between the roll and shoe and a paper web carried on a felt is taken through the nip with the water pressed from the web and into the felt during the travel through the nip.
In this type of construction, it is essential to be able to align the large roll and the shoe to bring them into perfect alignment for uniform pressing and for extended wear of the parts. The large roll is carried on end support bearings which must support the pressure of the press and these bearings must be kept in alignment with the roll end journals if satisfactory operation and wear is to be achieved. In addition to the misalignment problems of the bearings caused by shifting of the roll into alignment, the spacing between the ends of the bearings changes as the roll bends, and also changes as the temperature of the roll changes. These changes also tend to cause misalignment.
It is accordingly an object of the present invention to provide an improved extended nip roll structure wherein the problem of misalignment of the bearings at the end of the roll is avoided.
Another object of the invention is to provide an improved extended nip press wherein environmental circumstances such as change in temperature of the main roll and bending of the main roll do not cause bearing misalignment problems.
A further overall objective is to provide an improved extended nip press which has improved longer wearing bearing life eliminating the need for rapid replacement of bearings and journals.
Other objects, advantages and features, as well as equivalent structures which are intended to be covered herein, will become apparent with the teaching of the principles of the present invention in connection with the disclosure of the preferred embodiment in the specification, claims and drawings, in which: